<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <script src="https://cdn.jsdelivr.net/npm/vue@2.6.10/dist/vue.js"></script>
  <title>Document</title>
</head>

<body>
  <div id="App">
    {{ title }}
    <button @click="handelClick">Change</button>
  </div>
  <script>
    Vue.config.productionTip = false;

    const vm = new Vue({
      el: "#app",
      data () {
        return {
          msg: "hello",
        };
      },
      methods: {
        handlerClick () {
          /* 
             如何响应式的修改data数据:
             基本类型值直接修改(其实是重新赋值) 拥有响应式的
          */
          this.title = "hello world";
        },
      },
    });
  </script>
</body>

</html>